Dependence of the Mach number on the diameter of the SNR for E₀ = 10⁵¹  erg and n₀ = 0.5  cm^-3 for the two values of pressure P₀₄ = 2.17 (thick lines) and P₀₄ = 8.6 (thin lines). The solid and dotted curves describe the solution of the system of Eqs. (6)–(8) with and without the pressure of the ISM, and the dashed curves describe the Sedov solution without radiative cooling. The horizontal dash-dotted line corresponds to the point M_s = 2.